This Month in The Garden July 2020 with Derek Cox

Last month I mentioned how well my Rhododendrons were flowering, but the long dry spell during May caused many to go to seed very quickly, so I told Caroline, who is my gardening lady, not only to remove the seed heads, but also to prune back a number of the larger growers.

When pruning Rhododendrons always prune back to where there are a pair of green leaves as in the leaf axles there are dormant growth buds and it is these that will produce growth for the following years flowers.

I also have a number of dwarf Rhododendrons which never flower until June and early July, these are mainly native to mountainous areas of China, Japan and the Himalaya’s. I have grown Rhododendron saluense prostratum for over 40 years and even now it only forms a dense 18 inch (45cm) carpet of small dark green leaves. Single deep purple upturned flowers start to appear during early June. To me it is of great interest, but many people would not give it a second glance.

Rhododendron nakaharae, as its name suggests, comes from mount Nakahar in Japan and this forms a more loose carpet of hairy green leaves and its upright facing orange-red trumpets look very good during June in my rockery, I have a hybrid of nakaharae with the name ‘Alexander’ and a 30 year old eight feet (2.4m) diameter plant of this in one of my borders looks brilliant during June and early July as it is massed with upturned orange-red trumpets, see picture above.

Now from dwarf shrubs to a tall one Cotinus cogygria ‘Golden Spirit’, which many years ago I purchased as a new introduction from Holland. This came as a pot grown plant with a label saying it only grew 2.5 metres (seven/eight feet) tall. This just goes to show how misleading some plant labels can be as ‘Golden Spirit is now 15 feet (4.5m) tall and still putting on growth. However this is a glorious deciduous shrub/tree which has bright yellow leaves that add light to the darker green leaf trees nearby. You can keep this as a medium sized shrub by pruning the previous year’s growth back by two thirds during March.

Last year I wrote about Lavatera trimestris ‘Twins Hot Pink’ which I purchased at a garden centre for its large pink flowers. This is an annual that like most annuals flowers better when dead headed, but I let one branch go to seed and this year I germinated five seeds, now I have planted three plants at the rear of a bed of nonstop Begonias where their large pink flowers will give a lighter backdrop to the shrubs behind them.

Here I must point out that before I planted the Begonia’s I had to dig my dry soil over and water it before spreading garden compost over it and then forking it in. Never put mulch, or compost on the top of dry soil as this will then prevent any rain, or even a sprinkler from watering the soil beneath.

For the last 3 years I have grown Salvia ‘Hot Lips’ in a container and it is up potted each March and now sits in full sun in a 15 litre ornamental container. For me this amazing Mexican low growing shrub produces two different lots of flowers, the first in May appear as spires of small red flowers, but then as the second and remaining lot of flowers appear they are white with a brilliant red lip, hence the name ‘Hot Lips’ which will flower until late October. Being native to Mexico I have found it does not like cold wet winters, so during late October I lift the container into my cold greenhouse.

During the first week of June Caroline my lady gardener clipped two of my conifers to keep them compact. With most conifers you must only clip back to where there is still foliage otherwise they may not regrow. One exception to this is our native yew which I have seen pruned hard back to a trunk and the following spring the trunk started to sprout new growth.